Governor



Nov. 5, 1940.

L. E. WARNER El' AL GQVERNOR .Filed Jan. l?. 1939 3 sneetsfsheet 1INVENTORS. marqua "Wqme: By Hara/ al 7T Avery., MW

A TTORNEK l Nov. 5, 1940.

L. E. WARNER Er AL GOVERNOR Filed Jan. 17. 1939 .'5 Sheets-Sheet 2 Nov.5, 1940. L. E.. WARNER ET AL 2,220,305

` Govt-muon Filed Jan. 17, 19:59 5 sheets-sheet a PREM/; m//v'sr' inn 2PDB E-' 00mm; ,Park 0F `Sir/ras' Aw 22 m05 ro Mamvnr/765 97,1 50p/Dz y,6;

I ,05 l INVENToRs.

' Lawrence Warner.' v y A L /a rola 7. verj.

ATTORNEY.

Patented Nov. 5, 1940 2,220,306 GovEaNoa LawrenceE. Warner and Harold T.Avery, Oakland, Calif.. assignors to Marchant Calculating MachineCompany, a corporation of California Application January 17, 1939,Serial No. 251,361V

dclaims.

The present invention relates to speed regulating devices andparticularly to governors for electric motors.

Governors of the class to which the present invention relates comprisemechanism responsive to centrifugal force as the speed of the motorchanges, to operate switching devices in the power supply circuit forincreasing ordecreasing the mean voltage supplied to the motor so thatits speed is automatically maintained as nearly constant as possibleregardless oi changes in the driven load.

The principal object of the invention is to provide an improved governorof the class described y which will maintain the motor in smoothoperation at a predetermined speed although the driven load may varyover a wide range.

A further and important object in the invention is to improve governorso1 the class described by decreasing the voltage of the circuit orcircuits made and broken in governing operations.

A further and important object in the invention is to improve governorsof the class described by decreasing the amount of current passingthrough the circuit or circuits made and broken in governing operations.

A further and important object of the invention is to provide a governorof the class described in which the frequency of operation of theautomatically operated switching devices will be substantially reduced,whereby the life of the contact points thereof will be extended.

A further object of the invention is to increase the range of motorloads over which governing devices of the class described will functioneiliciently, without introducing factors which will Adecrease they lifeoi the contact points of the switching devices. A further object of theinvention is to increase the range of motor loads over whichgoverningdevices of the class described will function efilciently, withoutdecreasing the' accuracy withwhich the device will hold the motor to adesired speed.

The novel`features characteristic of the invention are set forth withparticularity in the' appended claims. The invention itself, however,together with additional objects and advantages thereof, will be bestunderstood from the following description of the specinc embodimentsthereof, when read in connection with the accompanying drawings. inwhich: Figure 1 is a view in side elevation of a gov- 5,-, ernormechanism comm il! scoorden@ with (Cl. 20o-80) the present' invention,certain parts being sectioned;

Figure 2 is a transverse sectional view taken substantially on the planeof line 2-2 of Figure l; c

Figure 3 is a fragmentary plane sectional view taken substantially onthe plane of line 3-3 of Figure 1;

Figure 4 is a longitudinal sectional view similar to Figure 1, butshowing a modified form of l0 device embodying the invention;

Figure 5 is a schematic wiring diagram of the apparatus; l

Figure 6 is a diagram showing the relative pressures that the varioussprings exert against 15 ball 62 (Figure 4), with diierent angularpositions of switch arm 22;

Figure 7 is a. schematic wiring diagram, showing a modiiied arrangementof resistors.

In general, the present governor system com 2o prises a plurality ofelectrical resistors which are adapted for connection into the supplycircuit of an electric motor for decreasing the voltage supply to themotor, which resistors are successively connected into said circuit bymeans `comprising 25 a speed responsive device connected to the motor.

With reference more specifically to the arrangement disclosed in Figures1 to 3 of the accompanying drawings, the present governor is adapted foruse in conjunction with an elec- 30 .tric motor I0, and comprises amounting plate II, secured by screws I2 to arms I3 integral with themotor, in spaced relation to an end Il thereof, and in spaced relationtoone end of the motor shaft I5 projecting through the end of the 35mots;- housing I0. Pivotally mounted on rod Il in a bracket I8, fixed byscrews 4I9 to the inner side oi the plate II, but insulated therefrom byplate 20 and bushing 2 I, is a switch arm 22, which extends across theline of the axisof the shaft I5 40 and is provided, adjacent its freeend, with spaced contact points 22 and 24 adapted to engage contactmembers 22 and 21, respectively, as the arm 22 is swung on its pivot rodI1. Electrical connection with the switch arm 22 is preferably 45 made,as here shown, by securing a ilexible conductor 28 to the pivoted end ofthe switch,arm, and to the bracket I8, which is provided with a lug 29extending beyond plate II (Figure 2) for Iexternal connection. 50

'I'he contact 22 is mounted upon a rigid bracket 32 secured to the innerside of the plate II by screws lI passing through la strip 22 andbushings 22, similar to\strip 20 and bushing 2|, so that the bracket llis insulated from the plate Il. An intermediate portion 34 of thebracket is offset `from the plate II so as to enclose the lower end ofswitch arm 22 between the oiset portion and the inner side oi. the plateIl.

The contact 21, in contrast to the contact 26, is mounted on a resilientmember, so that on counterclockwise movement of the arm 22, contacts 23and 26 will disengage prior to disengagement of contacts 24 and 21. Ashere shown (Figure 3) the contact support 36 consists of a at resilientstrip of metal, or the like, which is of substantially ,U shape and issecured to the inner side of the plate II by screws 31 and 38 passingthrough strip 32 and bushings 39 by which it is insulated therefrom.

The resilience of the strip 36 is such that contact 21, secured to thefree end of the strip, will resiliently press against and follow thecontact' element 24 on the arm 22, on movement of the arm away from thecontact member. The movementvof the contact support 36 is limited,however, by a stop 40, in the form of a block of insulation material,which is adjustablysupported on the plate I I by meansI of a screw 4Iand which engages the contact support 36 to limit its movement towardsthe plate II with the arm 22. The contact supports 36 and 36 beinginsulated from plate II, electrical connections are made with thesemembers, by means of terminal portions 42 and 43 at the ends of theportions of these members ixed to the plate.

.In accordance with the present invention,

. means are provided for displacing the switch arm 22 from the contacts26 and 21, so as to connect resistors, or the like, in the electriccircuit of the motor to reduce the voltage supply thereto as the load onthe motor is lightened and the motor speed thereby increased. Such meansinvolves the use of a speed responsive mechanism 58, which is connectedto the motor shaft I5, and which is operative to exert an outwardpressure against arm 22 in proportion to the square of the motor speedand thereby cause arm 22 to rock counterclockwise and to successivelydisconnect the contact members at successive posi-y tions of switch arm22.

The speed responsive mechanism, here shown, comprises an arm 5I, whichis pivoted at 52 on a bracket 53 secured to a hub 54 iixed to the shaftI5 by means such as screw 56, and actuated by centrifugal force uponrotation ofthe shaft to move the switch arm 22 toward the plate IIagainst a resilient resistance presentedby a spring 51 compressedbetween the arm 22 and a member 58 mounted on plate II. As shown inFigure 1, the lower end of the arm 5I extends into a slot 6I in the hub54 of the bracket 53 into alignment with the axis of shaft I5, andengages a ball 62 carried in an axially extending aperture in the end ofthe hub 54. 'I'he opposite side of the ball engages the head of a stud66 carried by the arm 22 in alignment with the axis of the shaft I5 butinsulated from the arm by plate 61 to which the stud 66 is secured andwhich in turn is secured to arm 22 by rivets 68 so that the stud 66 lieswithin an aperture 69 of arm 22. The function of the ball 62, as will beunderstood, is to transmit an axial force from the arm 5I to the switcharm 22.

The pressure exerted by the arm 5I against the switch arm 22 will beproportionate to the square of the rotational speed of the motor shaftI5, and the movement of'these members is controlled by the resistance ofthe spring 51, and the pressure exerted by the resilient Contact Support36. The resistance oilered by the spring 51 may be varied by manualadjustment so that displacement of the switch arm 22 at various speedsof the motor may be accurately controlled.

As here shown, the spring 51 is a helical spring which is supported atits ends by spring rests 58 and 59, which are supported, respectively,on the stud 66 and on the enlarged inner end of a screw 1I carried bythe plate II, the spring seat 59 being separated from the arm 22 bymeans of the strip 61 of insulation.

The compression of the spring 51 may be adjusted by a manual adjustmentof the screw 1i which, as shown in Figure l, is screwed into a plug 12which is, in turn, screwed into a bushing 13 on the plate II and may belocked thereto by a lock nut 14. The screw 1I is held in adjustedposition in the plug 12 by means of a nut 16, threaded on the screw 1Iand engageable against a spring 11 compressed between the nut 16 and theouter end of the plug 12, nut 16 being secured by a locking nut 18 and asleeve 19 being-provided to limit the range of adjustment in onedirection. The position of plug 12 determines the range of speeds withinwhich adjustment by screw 1I is possible, since the latter can beunscrewed only as far as permitted by the contact of its enlarged innerend with the plug 12.

Referring to the embodiment shown in Figurel 1, it will now be clearthat, upon acceleration of the motor, the switch arm 22 will bedisplaced away from the contact members 26 and 21 a distance determinedby the speed of the motor and the strength of springs 51 and 36 andthat, upon the motor attaining the predetermined speed, the switch arm22 will successively disengage the contacts 26 and 21. 'Ihepredetermined speed is controlled by the Icompression of the spring 51and by resilient contact support 36, the former of whichas was aboveseen, is subject to manual adjustment, and also by the latitude ofmovement permitted the'contact support 36, which, as above noted, isalso subject to manual adjustment. Thus, the apparatus may be set tobreak the contact between the switch arm 22 and the contact 26 atsubstantiallyany desired motor speed.

The breaking and making of the switch contacts which have been describedis used to throw into'and out oi the motor circuit, certain resistors`for changing the voltage supply to the motor, in accordance with theamount of load on the motor. The electrical circuit for accomplishingthis result is illustrated in Figure 5, wherein two resistors 80 and 8|are connected in the voltage supply circuit to the motor and the switchmechanism, so as to be normally cut out of the motor supply circuit bythe switch mechanism at y is supplied to the motor, the other side ofthe supply line being connected directly thereto by line 86.l Whentherst contact points 23 and 26 are opened by movement 4of 'arm' 22th'e'circuit to the motor is maintained from supply;.lead 82 by way ofmember 36, closed contactslfand 21,

' -exerted by the tip of centrifugal arm 6I and isv through arm 22 andlead 81 to resistor 80 and to motor lead 84. Thus, with the iirstcontacts 23 and 26 open, one resistor is thrown into the motor circuit.With contacts 24 and 21 also opened by further movement of arm 22, thecircuit to the motor is maintained from voltage supply line 82 to line81, line 88, resistance 8l and resistance 80, in series to motor lead84. Thus 'when both sets of contactsare open two resistances in seriesare thrown into the circuit to thereby further decrease the voltagesupplied to the motor.

Preferably, a condenser 89 is connected across the resistors in order toprotect the contact eiements of the switch against surges of currentcaused by the making and breaking of these contacts.

The resistors 80 and 8l may be proportioned in size with regard to thesize and characteristics of the motor and the variation of the operatingload. Usually, the sum of the resistance of these two resistors isselected to reduce the voltage supply to the motor to a point where theno-load speed of the motor is reduced to approximately its full loadspeed. The resistor 80 may then be of a size which will reduce the motorspeed under an average or mean operating load to substantially this samespeed. Thus, during starting, the motor is supplied a full line voltage,and, if the motor is sufciently loaded, the switch contacts will remainclosed and the full line voltage retained. If, however, the motor isonly subject to a light load, or if some of the load is removed, themotor will accelerate until switch contacts 23 and 26 are opened whenresistor 86 is placed in the circuit so as to check the rising motorspeed. If the action of resstor`80 is not sufficient, or if further loadisl removed from the motor; and motor continues to accelerate, switchcontacts 24 and 21 will be opened and suflicient resistance then placedinthe circuit to hold the motor speed to a desired maximum limit.

From the above description it is obvious that movement of contact arm 22will result whenever the counter-clockwise forces acting against it donot balance the clockwise forces acting against it. In the embodiment ofthe invention above described, the movement of the switch arm 22 iscontrolled by two outward forces and one inward force. 'I'he mainoutward force is that therefore proportional to the square of the motorspeed. The second outward force is that exerted by the flexible contactsupport 36, which force w decreases with outward movement of the switcharm 22. 'Ihe inward force acting onA arm 22 is that exerted by spring51. This force increases as arm 22 moves outwardly. From the above it isevident that for any set position of the arm 22 the centrifugal force isequal to the force of spring 51 minus the force of spring leaf 36. Asarm 22 moves outward the algebraic sum of the forces of spring 51 andspring 36 become greater, therefore the centrifugal force exerted bymember 5I must continue to increase if arm 22 is to continue its outwardmovement to where the second resistance is thrown into the circuit.

A modified form of the invention has been illustrated in Figure 4,wherein means are provided for causing arm 22 to move outwardly to openthe'second contact, thereby throwing th'e second resistance in thecircuit, without increasing the motor speed. This is accomplished by theaddition to the structure illustrated in Figures 1 to 3, which isidentified by the same reference -and throwing in @he first resistance80 (Figure numerals in this flgure, of an auxiliary spring 8|) (Figure4) whichis so arranged as to compensate for the increase of inwardpressure exerted by spring 51 and ilexible contact support 36 as the arm22 mov'es outwardly. This com- 5 la nut and bolt 93 movable in avertical slot 94 in plate II. The slide 32 may, for instance, beadjusted so as to position the axis of spring above the pivotal axis I1of arm 22 so that initially the force of spring 90 acts to move arm 22inwardly thereby adding to the force of spring 51. This corresponds tothe condition indicated in Figure 6, by line 90, with which arrangementas arm 22 moves outwardly the axis of spring 90 moves toward the pivotalaxis I1 thereby reducing its action against Iarm 22, further outwardmovement of arm 22 causing the axis of spring 90 to cross the pivotalaxis I1 and thereby exert an opposite force which acts to move arm 22outwardly.

Obviously it is not necessary that the line of action of spring 90 crossthe pivotal axis I1 as arm 22 rocks. Its entire action could be toeither side thereof so long as its point of attachment to arm 22 is suchthat its line of action moves rapidly toward or from axis I1 as arm 22rocks, and so long as the total force exerted by all springs equals thedesired value of centrifugal force.

In Figure 6, the pressures that the three springs exert against arm 22are shown diagrammatically for the positions of arm 22 as it movescounterclockwise. pressures exerted inwardly against arm 23 are shownabove the zero line and those exerted outwardly are shown below theline. Line 51 shows the increasing effect of spring 51. Line 36 showsthe decreasing outward pressure exerted by flexible support 36. Thevertical portion of this line indicates the point at which flexiblesupport 36 comes to rest against stop 40 (Figure 3), and it willtherefore exert no force when arm 22 moves outwardly beyond this point,at which the second contact starts to open. Line 90 represents thecompensating spring 90. The line R shows the resultant of the threesprings. Briefly, the governing will function as follows: With the motorat rest the resultant spring pressure is shown at A (Figure 6), as themotor accelerates the centrifugal member 5I exerts an increasing outwardpressure against switch arm 22. When this pressure slightly exceeds thespring pressure shown at point A, arm 22 willmove outwardly opening thecontacts 23 and 26 5). The governing at this point depends on the motorload, and will function i one of the four following manners: y

Case 1.--If the motor load is very light the voltage reduction resultingfrom throwingin the iirst resistance will not be suiiicient andthe motorwill continue to accelerate but at a lower rate; l Case 2.-If the motorload is a little greater the speed may remain constant; Case 3.-If theload is still greater the motor will decelerate at a low rate; whileCase 4.-If the load is near the maximum the motor will deceleraterapidly. Analyzing the rst case with very light load, 7

the centrifugal force of arm will continue to increase, therebyincreasing the outward pressure against arm 22. 'By following theresultant spring pressure curve R, it will be noted that the inwardpressure exerted by the combined springs is decreasing until point C isreached; therefore arm 22 is unbalanced outwardly and willv continue tomove outwardly. Movement of arm 22 beyond point C will cause an increaseof inward pressure up to point B. In the present illustration thecombined spring pressure at point B is the same as that at point A, andsince the outward pressure against arm 22 has continued to increase, thearm 22 will continue to move outwardly and cause contacts 24 and 21(Figure 4) to open and throw in the second resistance 8| which can besufficiently larger to cause the motor to decelerate rapidly enough sothat the inward force of the springs will overbalance the outward forceexerted by centrifugal member 5| and cause arm 22 to move inwardly untilcontacts 24 and 21 vagain close to shunt out the second resistance 8|,the governor will thus operate on the points 24 and 21 to maintain apractically constant speed, the same speed as that at which arm 22 rststarted to move away from the rst contact point 26.

Case 2, where the speed is constant after opening the iirst contact,will function the same as Case 1 in regard to motor speed, sincecentrifugal force will remain greater than corresponding spring pressureuntil 8| is thrown into cir" decelerate until the outward force due tocen' trifugal member 5| is reduced below point C.

. Arm 22 will then return inwardly under an increasing spring pres-sureuntil contact points 23 and 26 again make contact and cause the motor toagain accelerate until the outward pressure again becomes greater thanthe pressure at point A. This cycle will continue with the speed varyingbetween the limits necessary to unbalance the forces against arm 22 tocause the contacts 23 and 26 to make and break. It is obvious that thevertical portion of the resultant line R between points B .and C can bemade relatively short, thereby holding the speed uctuation under Case 3very small.

In Case 4, with a very heavy load the motor decelerates at a rate suchthat the outward pressure on arm '22 decreases faster than the inwardpressure of the spring against arm 22 decreases, thus the speed will becontrolled within very close limits at a point which gives an` outwardcentrifugal pressure approximately equal to that at point A.

It will be observed that this arrangement will result in the motorgoverning at exactly the same speed when governed by contact points 23and 26 under heavy load as when governed by contact points 24 and 21under light load, because of the fact that the resultant spring pressureagainst ball 62, and therefore the centrifugal force required to breakthe contacts is exactly the same at point A as at point B (Figure 6). Aslight loss of speed occurs, however, in changing from the latter to theformer. Obviously, by changing the strength of spring 90 (the slope ofline 90, Figure 6), or by changing the pressure that leaf 36 is capableof exerting against arm 22 (length BC, Figure 6), or by any of severalother similar changes, either the light load or heavy load point may bemade higher in governing speed than the other, instead of establishingthe two at identical speeds as in the above illustration.

An' alternate arrangement of resistors and electrical circuits is shownin Figure 7. This arrangement accomplishes the same purpose as thearrangement previously described. In this arrangement the two resistorsare arranged in parallel connection such that the resultant parallelresistance is thrown into the supply circuit to the motor when the rstcontacts 23 and 26 are opened. When the second contacts 2B and 21 areopened the circuit to one of the resistors is opened leaving only oneresistorin the circuit and thereby further increasing the resistance inthe supply circuit to the motor. This circuit can be followed in Figure7. When both contacts are closed the circuit from the voltage supplyline Q6 to the motor is completed by way of lead 91, arm 22, contacts 23and 26, and lead 38 to the motor lead 99. With the iirst contacts 23 and26 open, the circuit from supply line 96 to the motor is maintained byway of leads 91, arm 22, contacts 24 and 21, lead illl to one of theparallel resistances |03, and also from the supply line 91 by way ofleads |04 and |05 through the other parallel resistance |06 to the motorlead 99. If both contacts are open the current passes from lead 91 toleads |04 and |05 to a greater resistance H06 and to lead 99, thuscutting out the lesser resistance |03. This second arrangement has theadvantage over the previous arrangement in that when the rst set ofcontacts 23 and 26 are closed the current to the motor does not have topass through the second set of contacts 24 and 21. A further advantageof the arrangement shown in Figure 7 is that two resistances are throwninto circuit when the greater amount of heat must be dissipated, and oneresistance when a less amount of heat is to be dissipated, while thereverse condition exists in the Figure 5 arrangement. A greater amountof heat is generated with a lower resistancein circuit, and sinceresistance 80 (Figure 5) is thrown into the circuit alone, it

must dissipate a greater amount of heat than is dissipated whenresistances 80 and 8| are connected in series. In the Figure '1arrangement, on the other hand, resistances |03 and |06 are connected inparallel when both are in circuit, and therefore set up a lowerresistance than is set up when resistance |36 alone is in circuit. Hencewith this arrangement there will be less heat developed`when oneresistance is in circuit than when both resistances are in circuit, thusmaking possiblethe use of more economically sized resistances than ispossible with the Figure 5 arrangement.

One of the important applications of the present invention is'the use ofthe same in coni machines and calculators, where a great variance ofload is applied on the motor, as a result of the use of various numbersor combinations of the keys and associated counting mechanisms. However,the invention has a relatively wide `application, as will be apparent tothose skilled in the art. Also, although speciic embodiments of theinvention have been described herein, it will be apparent to thoseskilled in the art to which the invention appertains, that manymodifications thereof are possible, and it is to be understood that theinvention is not to be considered .as restricted to the forms shownexcept insofar as is necessitated by the prior art and by the spirit ofthe appended claims.

We claim:

1. In a device of the class described, a rotatable member having a leverpivotally mounted thereon and movable by centrifugal force effectiveduring rotation of said member, a switch arm displaceable by said leverand provided with a plu-r rality of electrical contact points, resilientmeans arranged to furnish progressively increasing resistance tomovement of said switch arm by said lever, resilient means arranged tofurnish progressively decreasing assistance to movement of said switcharm by said lever and including an electrical contact point engaging oneof the aforesaid contact points on said switch arm, and a ilxedelectrical contact point engaging the other 'of the aforesaid contactpoints on said switch arm.

2. In a device of the class described, a rotatable member having a leverpivotally mounted thereon and movable by centrifugal force effectiveduring rotation of said member, a switch arm displaceable by said leverand provided with a plu- -rality of electrical contact points, a xedelectrical contact point engageable with one of the aforesaid contactpoints, a spring arranged to furnish progressively increasing resistanceto movement of said switch arm by said lever, a rst resilient meansarranged to furnish progressively decreasing assistance to movement ofsaid switch arm by said lever and including an electrical contact pointengageable with one o! the aforesaid contact points on said-switch arm,and a second resilient means comprising a spring positioned on said armand positioned so as to produce a rocking moment rst on one side andthen on the other side of the pivotal mounting thereof in progressiveangular positions o! laid -pivotally mounted switch arm displaceable bysaid lever, and switch means voperable by displacement of said arm;characterized by the provision of resilient means opposing displacementof said arm by said lever in combination with a spring positioned onsaid arm so as to produce a rocking moment first on one side and then onthe other side of the pivotal mounting thereof in progressive angularpositions of said arm and to thus first oppose and then aid displacementof said arm by said lever as such progressive angular displacement takesplace,

A:fwhereby the total resistance offered to displacement of said arm bysaid lever remains substantially constant during angular displacement ofsaid arm.A

4. A device of the class described comprising a l rotatable memberhaving a lever pivotally mounted thereon and movable by centrifugalforce effective during rotation of said member, a pivotally mountedswitch arm displaceable by said lever, and switch means operable bydisplacement of said arm; characterized by the provision oi resilientmeans opposing displacement of said arm by said lever in combinationwith a spring positioned on said arm adjacent the pivotal mountingthereof so as to produce a rocking moment which changes rapidly withchanges in the angular position of said arm, whereby the totalresistance offered to displacement of said arm by said lever remainssubstantially constant during angular displacement o! said arm.

LAWRENCE E. WARNER.

HAROLD T. AVERY.

